Write about Green chemistry.

     Green chemistry also called sustainable chemistry, is an area of chemistry and chemical engineering focused on the design of products and processes that minimize or eliminate the use and generation of hazardous substances.  While environmental chemistry focuses on the effects of polluting chemicals on nature, green chemistry focuses on environmental impact of chemistry, including reducing consumption of nonrenewable resources and technological approaches for preventing pollution.

     The overarching goals of green chemistry-namely, more resource-efficient and inherently safer design of molecules, materials, products, and processes-can be pursued in a wide range of contexts.

     green chemistry emerged from a variety of existing ideas and research efforts in the period leading up to the 1990s, in the context of increasing attention to problems of chemical pollution and resource depletion.  The development of green chemistry in Europe and the United States was linked to a shift in environmental problem-solving strategies;  a movement from command and control regulation and mandated reduction of industrial emissions at the "end of the pipe", towards the active prevention of pollution through the innovative design of production technologies themselves.  The set of concepts now recognized as green chemistry coalesced in the mid-to late-1990s, along with broader adoption of the term ( which prevailed over competing terms such as "clean" and "sustainable chemistry).